This application claims the priority of Japanese Patent Applications No. 8-172892 filed on Jun. 12, 1996 which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a light source device for an endoscope and, more particularly, to a structure for shielding the noise produced in a light source device for an endoscope provided with a lamp house for accommodating a lamp as the light source.
2. Description of the Related Art
FIG. 8 is a side elevational view of a conventional light source device for an endoscope. A box body 2 of a light source device 1 is provided with a lamp house 4 accommodating a xenon lamp 3. A connector receptacle 5 in the front part of the light source device 1 is so composed as to receive a connector 6 of a scope and the incident 6A end of a light guide is disposed in such a manner as to face a light emitting portion of the xenon lamp 3 and the lamp house 4. The light of the xenon lamp 3 therefore is introduced to the end of the scope through the incident end 6A of the light guide and irradiates an object of observation.
The lamp house 4 is made of a metal material in the shape of a rectangular parallelopiped so as to prevent the light of the xenon lamp 3 from leaking outside and to shield the noise produced from the lamp 3. An opening 7 through which the xenon lamp 3 is exchanged is provided in the side surface of the lamp house 4. A cooling fan (not shown) is disposed on the opposite side surface of the lamp house 4 so as to cool the xenon lamp 3.
An opening 9 slightly larger than the opening 7 is provided in the box body 2 which accommodates the lamp house 4. A lamp hatch (door) 10 is attached to the opening 9 with hinges 11 so as to be rotatable. The lamp hatch 10 is opened when the xenon lamp 3 is exchanged and the xenon lamp 3 is taken out and a new one is inserted through the opening 7. The lamp hatch 10 is screwed to a supporting portion 12 provided in the opening 9 by utilizing ports 13, 14.
The opening 7 of the lamp house 4 is also utilized as an air suction hole and an air outlet hole when the xenon lamp 3 is cooled. More specifically, when the cooling fan for the xenon lamp 3 sucks air, the opening 7 serves as an air outlet hole, while the cooling fan discharges air, the opening 7 serves as an air suction hole. The air suction and air exhaustion are executed through a multiplicity of slits formed in the lamp hatch 10.
In the above-described light source device 1, however, the noise shielding effect disadvantageously is lessened due to the opening 7 provided in the lamp house 4. A high-frequency noise (e.g., noise having a frequency n times as high as 110 kHz) is produced due to the discharging operation of the xenon lamp 3, or from the wiring from the switching power source for lighting the xenon lamp 3 to the xenon lamp 3. In order to shield the noise, the xenon lamp 3 is accommodated in the lamp house 4. However, a part of the noise leaks to the outside of the lamp house 4 through the opening 7 and exerts a deleterious influence on other devices and equipments.